The present invention relates to a control system for direction control valve and, more particularly, relates to a control system, which is specifically adapted for controlling valves like the one disclosed in U.S. Pat. No. 3,924,656 issued to Hanser et al. on Dec. 9, 1975, this valve, in turn, being particularly useful in controlling reversible hydraulic actuators used for effecting vertical adjustment of a motor grader blade in a manner similar to that disclosed in co-pending U.S. patent application Ser. No. 712,606 filed by Sisk et al. on Aug. 9, 1976 now U.S. Pat. No. 4,057,701.
In the control system disclosed in the aforementioned patent application, the operator must hold a normally open, manually operable switch in a closed condition in order to maintain a float-effecting condition in the direction control valve. This holding thus occupies the use of at least one hand of the operator during anytime the blade is operated in a float mode and such is not desirable in view of the many other functions which require the use of the operator's hands.